Rss-Bridge/lib/HttpCachingBridgeAbstract.php

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<?php
require_once(__DIR__ . '/BridgeInterface.php');
/**
* Extension of BridgeAbstract allowing caching of files downloaded over http.
* TODO allow file cache invalidation by touching files on access, and removing
* files/directories which have not been touched since ... a long time
*/
abstract class HttpCachingBridgeAbstract extends BridgeAbstract {
/**
* Maintain locally cached versions of pages to download, to avoid multiple downloads.
* @param url url to cache
* @return content of the file as string
*/
public function get_cached($url){
// TODO build this from the variable given to Cache
$cacheDir = __DIR__ . '/../cache/pages/';
$filepath = $this->buildCacheFilePath($url, $cacheDir);
if(file_exists($filepath)){
$this->debugMessage('loading cached file from ' . $filepath . ' for page at url ' . $url);
// TODO touch file and its parent, and try to do neighbour deletion
$this->refresh_in_cache($cacheDir, $filepath);
$content = file_get_contents($filepath);
} else {
$this->debugMessage('we have no local copy of ' . $url . ' Downloading to ' . $filepath);
$dir = substr($filepath, 0, strrpos($filepath, '/'));
if(!is_dir($dir)){
$this->debugMessage('creating directories for ' . $dir);
mkdir($dir, 0777, true);
}
$content = $this->getContents($url);
if($content !== false){
file_put_contents($filepath, $content);
}
}
return str_get_html($content);
}
public function get_cached_time($url){
// TODO build this from the variable given to Cache
$cacheDir = __DIR__ . '/../cache/pages/';
$filepath = $this->buildCacheFilePath($url, $cacheDir);
if(!file_exists($filepath)){
$this->get_cached($url);
}
return filectime($filepath);
}
private function refresh_in_cache($cacheDir, $filepath){
$currentPath = $filepath;
while(!$cacheDir == $currentPath){
touch($currentPath);
$currentPath = dirname($currentPath);
}
}
private function buildCacheFilePath($url, $cacheDir){
$simplified_url = str_replace(
['http://', 'https://', '?', '&', '='],
['', '', '/', '/', '/'],
$url);
if(substr($cacheDir, -1) !== '/'){
$cacheDir .= '/';
}
$filepath = $cacheDir . $simplified_url;
if(substr($filepath, -1) === '/'){
$filepath .= 'index.html';
}
return $filepath;
}
public function remove_from_cache($url){
// TODO build this from the variable given to Cache
$cacheDir = __DIR__ . '/../cache/pages/';
$filepath = $this->buildCacheFilePath($url, $cacheDir);
$this->debugMessage('removing from cache \'' . $filepath . '\'');
unlink($filepath);
}
}